1. Field of the Invention
The present invention relates to a method of fabricating ZnO nanostructures and its apparatus, and more particularly, to a method of fabricating ZnO nanostructures from Zn gas, which is produced by a reduction process between ZnO powder and graphite, on a silicon substrate, wherein various types of nanostructures are reproducibly generated by adjusting the processing temperature and the mixed ratio between oxygen and argon gases, which are introduced into the interior of a reaction tube as carrier gases, and its apparatus.
2. Description of the Background Art
Nanostructures are generally in the range of from a few nanometers to a few hundred nanometers and exhibit novel physical and chemical properties due to their nanoscaled dimensions unlike bulk type materials. These nanoscaled building blocks can be used in fabricating highly sophisticated and/or functional nanodevices in the fields of electronics, optoelectronics, and electrochemistry. To date, nanoscaled building blocks such as quantum dots, nanopowders, nanowires, nanotubes, quantum wells, nanofilms, and nano composites have been intensively investigated, especially for the bottom-up approaches to nanoelectronics (Y. Xia at al, Advanced Materials, Vol. 15, p. 353 (2003); G. Tseng, Science, Vol. 294, p. 1293 (2001)).
In the meantime, ZnO has been in the spotlight as a promising material for electronic devices, surface acoustic wave devices, optoelectronic devices, piezoelectric devices, and chemical sensors, transparent electrodes due to its wide bandgap, optical transparency, and tunable conductivity.
Furthermore, advances in epitaxial growth technology have promoted the developments of various optoelectronic devices including blue/green light emitting diode and laser diode.
A typical example of ZnO nanostructure fabrication is synthesis of nanowires (Y. Xia at al, Advanced Materials, Vol. 15, p. 353 (2003); M. H. Huang et al., Advanced Materials, Vol. 13, p. 113 (2001)).
Various types of 1-dimensional ZnO nanostructures (nanowires, nanotubes, etc.) have been fabricated using such processes as carbothermal reduction and chemical vapor deposition, and they were also shown to be applicable into optoelectronic devices, laser diodes, chemical sensors and the like.
Although there are a number of reports on the ZnO nanostructures, the feasibility of realizing highly integrated functional devices is still questionable due to the difficulties in alignment and assembly of the nanostructures. In this regards, creation of nanoscaled building blocks of various size and shapes is crucial. In this invention, we invented various ZnO nanostructures, especially ultrawide ZnO nanosheets and nanowire arrays which can be easily manipulated by conventional lithography and/or assembly techniques, while maintaining nano-sized features.